Ch 20

Question 1

3 major types of muscles

Answer 1

skeletal - striated
~ voluntary with no hormonal influence
cardiac - striated
smooth - unstriated

Question 2

all 3 types of muscles use ___ & _____ filaments

Answer 2

thin & thick filaments

Question 3

what is needed for muscle contraction

Answer 3

calcium

Question 4

describe innervation between the 3 muscle types

Answer 4

skeletal - somatic nervous system initiates contractions

all other are autonomic nervous system

Question 5

where are gap junctions present in the 3 types of muscles

Answer 5

present in single unit smooth & cardiac

Question 6

describe 3 muscles types in terms of troponin and tropomyosin

Answer 6

skeletal
- both preset

smooth
- tropomyosin only

cardiac
- both present

Question 7

Ca2+ regulation between the 3 muscles types

Answer 7

skeletal - Ca2+ and troponin
smooth - Ca2+ and calmodulin
cardiac - Ca2+ and troponin

Question 8

which of the muscles types can be fast to contract

Answer 8

skeletal

Question 9

muscles are important for ______, particularly

Answer 9

locomotion, particularly skeletal

Question 10

compare a fascicle and myofibril

Answer 10

fascicle - bundle of muscle fiber
* organizes muscle fibers(cells) for coordinated movement

myofibril - rod like structure inside each muscle fiber
* responsible for the actual contraction of muscle fiber

Question 11

organizational levels of skeletal muscle (order)

Answer 11

muscle
fascicles
muscle fiber
myofibril
sarcomere
myofilament

Question 12

what is the sarcolemma

Answer 12

cell membrane for muscle fiber

Question 13

where is calcium stored in the muscle fiber

Answer 13

the sarcoplasmic reticulum (SR)

Question 14

describe the parts of a myofibril (4)

Answer 14

1 sarcomere is encased within Z discs

I band = only THIN filaments
H band = only THICK filaments
A band = has both that overlap

Question 15

thick filaments are ___ and thin are ____

Answer 15

thick = myosin
thin = actin

Question 16

how to skeletal muscles contract? what happens to the H zone? I band?

Answer 16

by thick and thin myofilaments sliding by one another

H zone & I band NARROW

Question 17

3 parts of troponin and what they bind to

Answer 17

TnC= bind to Ca2+
TnI = binds to actin (inhibit contraction)
Tnt = binds to tropomyosin

Question 18

in a relaxed muscle state is there binding to Ca2+?

Answer 18

NO

Question 19

describe what happens when Ca2+ binds to troponin

Answer 19

troponin will change shape pulling tropomyosin away from the myosin-binding sites on actin
- now myosin heads are exposed and can bind to actin (thin filaments), forming a cross-bridge = contraction

Question 20

describe tropomyosin

Answer 20

2 coiled a-helices
- covers myosin binding sites on actin

Question 21

describe myosin (thick) filaments and the two important sites on the cross bridge

Answer 21

• has myosin head(cross bridge) that moves in muscle contraction

cross bridge:
- actin binding site
- ATPase site

Question 22

in contraction do the thick/ thin filaments change length?

Answer 22

NO just overlap more

Question 23

1 cross bridge cycle uses __ATP and moves the actin filament about ___ nm

Answer 23

1 ATP and moves about 10nm

Question 24

describe DHPR

Answer 24

voltage gated dihydropyridine receptor
- opens with depolarization causing Ca2+ to enter the cell (voltage sensitive)

Question 25

describe RyR

Answer 25

ryanodine receptor - calcium channel in the SR that releases stored Ca2+ into the cytosol *mechanically sensitive

Question 26

describe muscle relaxation steps

Answer 26

1. Ca2+ is taken back up into the SR via Ca2+ ATPase 2. tropomyosin covers back back up again - there is acetylcholinesterase which breaks down ACH (so not much AP signal propagates to t tubule)

Question 27

concentric, eccentric & isometric contraction

Answer 27

concentric (isotonic) = muscle shortens eccentric = muscle lengthens isometric = stays same length

Question 28

tension will ____ with too much or not enough overlap of filaments

Answer 28

decrease

Question 29

passive vs active tension

Answer 29

active = - forced generated by contraction / cross bridge cycling between filaments passive = - stretching of muscle NOT contraction

Question 30

muscle twitch is following a ____ period

Answer 30

latent period

Question 31

contractile summation

Answer 31

sum together to get more forceful contractions * tetanus (high frequency of stimulation = long contraction)

Question 32

as the velocity of a contraction increases the amount of force e produced _____

Answer 32

decreases

Question 33

how can you change power

Answer 33

by increasing force or velocity

Question 34

order of contraction time (ATP supply) lengths (3)

Answer 34

least - creatine phosphate anaerobic glycolysis most - Oxidative phosphorylation (aerobic) * high ATP gen

Question 35

for a short run you use ? medium? long?

Answer 35

short - creatine phosphate medium - glycolysis long - oxid.phosphorylation

Question 36

3 muscle fiber types

Answer 36

slow oxidative - low intensity, endurance activities (posture) fast oxidative - medium intensity activities (sprinting/walking) fast glycolytic - short term intense/powerful movements (hitting a baseball) *few mitochondria *prone to fatigue *low myoglobin *white color NOT red *larger, high force

Question 37

3 muscle adaptations

Answer 37

1. myosin isoforms 2. troponin isoforms 3. high amount of Ca2+ ATPase pumps

Question 38

neural control has ___ motor neuron units ? which are recruited first

Answer 38

3 units smallest muscle fiber recruited first, then larger as stimulus increases

Question 39

vertebrates have __ motor neuron where invertebrates (arthropods) have ____ neuron’s

Answer 39

vertebrates - 1 motor neuron invertebrates - multiple neurons (excitatory/ inhibitory)

Question 40

smooth muscle and process

Answer 40

- no troponin = active site always available to bind - slow - Ca2+ bind to calmodulin (instead of troponin) which activates myosin light chain kinase -> phosphorylates myosin, allowing it to bind with actin = crossbridge cycling/ contraction

Question 41

multi unit vs single unit smooth muscle

Answer 41

single unit - gap junctions, spont, contracts as a unit multi unit - discrete units are stimulated, no gap junctions, non spont.